Screening and mutagenesis, in conjunction with two-dimensional electrophoresis, will be utilized to detect genetic variations at ribosomal protein loci in Drosophila. The loci will then be localized by genetic analysis. The possible coordinate control of ribosome biogenesis will be investigated using genetic mutants affecting ribosomes, and specific drugs, studying synthetic rates of RNA and protein in isolated ovary and tissue culture systems. Specific and sensitive serological procedures will be employed to quantitate ribosomal protein synthesis, while gel electrophoresis and scintillation spectrography will serve to measure r-RNA synthesis. Protein synthesis and m-RNA stability will be studied in mutants known to affect t-RNA structure or abundance. Factors influencing m-RNA stability will be investigated. Detailed biochemical and physiological studies will be carried out on several polymorphic enzyme systems to determine the possible adaptive significance of allozymes. A specific molecular model for single locus heterosis will be tested.